For many years, birds and animals have operated unattended cameras by means of trip lines.
It is, of course, well known that such big game animals as deer follow established game trails and a recent development of interest to hunters recognized that a trip line could as well be used to interrupt the operation of a battery operated, digital electric clock and thus provide accurate information of the time a deer came along the trail. The trail was perhaps chosen because of nearby evidence such as tracks, pawings and rubbings providing evidence that the deer was a large buck.
The small and inexpensive electric clocks, otherwise well suited for such a use, require that their circuitry be modified by the addition of leads which, when connected, will stop the clock. In the above referred to development, the switch means employed to control the added leads had to respond to an indirect pull as it was a flexible and somewhat resilient member anchored at one end in the device with its other end seated between the contacts of the leads. The intermediate portion of the member was exposed as a bow to which the trip thread was attached. Furthermore, no means were provided to provide a reliable indication of the direction in which the tripping animal was travelling.